Control system



Dec. 11, i945 E. o. SETTE RBLADE ,6

- CONTROL SYSTEM Filed July 2, 1942 I 4 Sheets-Sheet 1 IINVENTOR f? 06577225440: Q 44 I HIS NE Dec.- 11*, 1945. E. o. SETTERBLADE 2,390,619

' CONTROL SYSTEM",

Filed July 2, 1942 4 Sheefcs-Sheet 2 7 izsflaz" INVENTOR 542' 055775234405 engine than has hitherto been the case.

Patented Dec. 11, 194

UNITED STATES {PATENT OFFICE' CONTROL SYSTEM Earl 0. Setter-blade, Glen Rock, N. J asslgnor to Wright Aeronautical Corporation, a corporation of New York Application July 2, 1942, Serial No. 449,537

7 Claims. This invention relates to automatic controls operable under the influence of fluid pressures,

and'is particularly related to' automatic controls responsive to fluid pressure differences existing from time to time within the intake systems (either air or mixed air and fuel systems) of internal combustion engines. Such controls are ordinarily arranged to automatically vary the settings of accessory devices associated with and playing a part in the operation of the internal combustion engines, so that those devices will always be effective in accordance with the par- .ticular requirements of the engines under varying conditions of use.

It is a primary object of the present invention to provide an automatic control of the type described which shall operate largely independent of and without regard to atmospheric pressure, and which shall. thus, be particularly adapted for use with aircraft engines where major differences in altitude produce varying values of atmospheric pressure.

It is a further object to provide an automatic control of the type described which shall be more responsive and sensitive to varying power outputs and load conditions of an internal combustion Up to the present time it has been customary, in aircraft engines, to set the magneto, during the manufacture of an engine, at an optimum spark timing which is generally satisfactory for all ccnditionsof engine operation, thereby relieving the pilot of manually operating a sparkcontrol lever from time to time during his handling of the aircraft. But, because of this rigid setting of the ignition system, the engine does not always operate at maximum efllciency, with the result that much fuel is wasted, and wear and tear on .the engine isgreater than it would otherwise be.

With the above in mind, it is a specific object of the invention to provide an automatic system for controlling the spark timing ofan aircraft magneto relative to an aircraft engine in accordance with the varying requirements of the engine during operation.

In accomplishing these objects of the invention, I make use of the varying differentials in pressurewhich exist, or which canbe made to exist,

3 between two or more locations within the air or air and fuel intake system or systems of an internal combustion engine, from time to time during operation, thereof, such pressure differentials providing an excellent measure of the varying operative characteristics of the engine.

The pressure differentials, made-effective and put into action by a suitable pressure-responsive device, such as a diaphragm. Svlphon, or bellows against which -the differential pressures are caused to act, are advantageously used to drive a valve mechanism controlling fluid pressure within a conduit. The fluidpressure thus becomes the agency whereby other mechanism is set to operate as desired.

In the instance of control of the spark timing of an aircraft magneto, relative to the aircraft engine, it is preferred, according-to the invention, that the drive connection between the magneto and "engine proper be made adjustable, for changing the spark timing, instead of rigid with fixed spark timing, as is usual, and that. it be so arranged as to be adjustable by means of fluid pressure acting thereon. Under these conditions, a special conduit may be provided from the pressure oil system used for lubricating the engine, and may be valved by means of the valve mechanism which is driven by the pressure-controlled diaphragm or Sylphon. Under this unique pressure control, the valve device itself controls the pressure flow of oil through the special conduit, for adjusting-action against the aforementioned oil through the special conduit, the oil pressure effects the adjustment which changes the spark setting, and maintains the drive connection in the new adjusted position until movement of the valve device releases the pressure and permits the drive connection to assume its original setting of spark timing. Inthis manner the spark timing of the ignition system of the engine is varied in accordance with engine performance.

Further objects and features of the invention will be apparent from the following detailed description .of the preferred embodiments illustrated in the accompanying drawings.

In the drawings:

Fig. 1 represents a fragmentary elevation,

taken from the rear, of a conventional type of placement of the control device of the invention relative to the magneto drive shaft;

Fig. 3, an enlarged vertical section taken on the line 3-3, Fig. .2, the spark being fully retarded;

.Fig. 4,.a vertical section taken on the line H,-

Figs. 2and 3, and drawn to the same scale as the view of Fig. 3;

Fig. 5, a vertical section taken on the line'l -l,

Fig. 6, a schematic view of the system of the prior figures,- and showing the positions of the component elements when spark is fully advanced;

-'Fig. 7, an enlarged detail view of the valve device as shown schematically in Fig. 6, but taken when the engine is idling with spark retarded;

Fig, 8, a view corresponding to that of Fig. '7, but taken when the engine is running at cruising speed with spark advanced;

Fig. 9, a view corresponding to those of Figs. 7 and 8, but taken when the engine is running at high speed with spark retarded;

Fig. 10, a graph plotted between propeller load and pressure differentials, or metering force, portraying the relationship therebetween in terms of spark setting pursuant to the invention;

Fig. 11, a diagrammatic view of an engine manifold illustrating a somewhat different arrangement for producing the varying differential pressures used by the control device of the invention;

Fig.. 12, a sectional view showing how the control system of the invention can be applied to the opening and closing of the engine cowling at appropriate times, rather than to the control of spark setting; and

Fig. 13, an enlarged sectional view of a portion of the mechanism of Fig. 12.

The specific .embodiments of the invention here illustrated and described in detail merely exemplify the generic possibilities inherent in the inventive concepts disclosed.

A-highly advantageous system for controlling the setting of the so-called spark event of an aircraft engine is illustrated in Figs. 1 through 10.

The engine, indicated generally ll), Figs. 1, 2, and 6, is a standard, radial, air-cooled type provided with a magneto ll of standard manufac-' ture. As is conventional, the magneto if is driven by the crank shaft Illa of the engine in by means' of drive gear 52, intermediate reduction gearing l3,- driven gear l4, and a drive connection or coupling, here indicated generally at 15.

The control system of the invention is incorporated in this standard aircraft assembly with a minimum of change in the accepted'design of the latter, and with a minimum of additional mechanism.

Whereas in the standard assembly, the drive connection If: would be made by means of a unitary rigid shaft allowing no adjustment during operation of the engine, the shaft connection is accomplished in accordance with the invention by means of preferably a bi-sectional spline coupling having separate spline sections loosely fitted together so that one may be rotated a limited distance relative to the other, on the common axis of rotation, during operation of the engine.

This splined shaft connection iswell illus-" trated in Figs. 3, 4, and 5. The drive shaft I6 of the magneto II has tightly fitted over its fluted stub end the internally ribbed tubular end ll-I of spline section II, the internal ribs mating with the flutes, as illustrated, so the drive shaft and spline section are fixed for rotation together. The spline section 11 has the male spline formation l'I--2, which is here shown as having four radial splines or vanes IIa extending circumferentially thereof. A second spline section l8 has a flanged end I8-'|, secured to the driven gear L4, as by means of the machine. screws l9, and has a female or socket spline-receiving formation 18-2. This splinereceiving formation has internally extending .ridges I811, mutually spaced to form grooves l8b' for accommodating the splines IIa f the male spline formation ll-2.

The thickness of a spline l'la is less than the width of a corresponding groove l8b by an amount which provides the desired leewa for rotation of shaft I6 relative to and independently of driven gear M, in the adjusting of the setting of the magneto H from retarded to advanced spark timing.

The two spline sections El and 68 have their male and female spline formations ll-l and l8-2, respectively, interfltted or mated to provide the adjustable drive connection or coupling between engine and magneto. They may be held in proper longitudinal alignment by means of a special bolt 20 extending axially therethrough and provided with an enlarged circular head Eta, which seats against an internally protruding, circumferential ring i8ia of spline sections l8. The bolt 20 is not cinched so tight as to interfere with rotation of one spline section relative to and independently of the other.

The drive connection or coupling is house within a casing 2!, which may be bolted to the housing of magneto H, as at 22,- Figs. 2 and 3. A sleeve bushing 23 is disposed between the drive connection or coupling proper'and the casing 2|.

It is desired that the drive connection or con pling be packed in its housing substantially fiuidtight, for a purpose which will appear hereinafter. Accordingly, sleeve bushing 23 has a flanged end 23a which is constantly pressed against the flange of the end Iii-l of spline section l8, by means of a relatively short coil spring 24 acting against the opposite endof the sleeve bushing. An annular end plate 25. is tightly splined to the fluted end of magneto shaft l5, and has an annular groove 28 formed on the inner surface thereof for tightly receiving a circumferential portion of a ring 21, The ring 21 has an external circumferential rib 21a which provides, at one Side thereofiabutment for the coil spring 24, and, at the opposite side thereof, a circumferential seat for the retaining washer 28, which is securely bolted to the housing 2|, as at 29. i V

The crank shaft Illa of the motor I rotates in the direction of the appended arrow, Fig, 1, and

Accordingly, with no other forces acting, the

ridges lBa of spline section ill will abut against the splines Ila of spline section I! during operation of the engine, and will serve to rotate mag-' neto shaft It in the direction of the appended arrow, Fig. 3., I l Under these conditions, the spark timing of the magneto relative to the engine is in retard setting. The control system of the invention contemplates, however, that the spark timing shall be advanced during operation of the engine, as required by variations in engine performance. This is accomplished by projecting fluid under pressure through suitable passages in the ridges l8 against the'abutting faces of splines Ila, thereby serving to rotate spline section I! forward relative to spline section ill to the limited extent permitted by the space available in grooves I81), and acting to hold the spline section l1 in its new forward position until the fluid pressure supply is cutoff and the pressure released.

' The oil maintained under pressure in the lubricating system (shown schematically at 30, Fig. 6)

generally 32 and described in detail hereinafter,

the valve mechanism being itself automatically '2l, as passage 33a, and

, a return pipeline 50.

ineffective circulation of oil from vided as an offshoot of the main lubricating system 30. The valve mechanism 32 is partially housed in a branch Zla of casing 2|, and the special conduit system 33 passes through casing through branch am, as passage 33b.

The valve mechanism 32 comprises the cylindrical valve body 35, Fig, 4, having the reduced and conically terminating portion 35a, which fits tightly into a correspondingly bored portion of the intermediate cylindrical casing 35. A flanged collar 3?, bolted as at 38; to the engine housing 39, serves place.

Three valve heads 40, secured in mutually spaced relationshipon the,valve stem 4!, are

' slidably fitted into valve passage 42, which is defined within valve body 35, and are adapted for reciprocative movement therein. I

The intermediate cylindrical casing 35 aids in defining the oil-flow passages 33b, and hasan extending annular portion 36a which is snugly fitted about the external periphery of the splinereceiving socket formation Ill-2 of spline section l8.

The oil-flow passage 33b communicates with oil-flow passage 33c, which extends through the reduced portion 35a of valve body 35 and opens into the valve passage '42.

Extending from communication with valve passage 42, at a location offset with respect to the port opening of oil-flow passage 33c, and passing through substantially the length of the reduced valve body portion 35a to outlet at the conical terminal end thereof,is oil-flow passage 33d.

And communicating with this outlet terminus ofoil-fiow passage 33d, is the annular oil-flow passage 33e, which is provided by the annular portion 36a of intermediate casing 36.

It will be remembered that the annular casing portion 35a encircles the outer periphery of splinereceiving socket portion I B-2 of spline section l8. Accordingly, in order to establish oil-flow communication between annular passage 33c and the interior of spline shaft connections l5, oiljet passages 33] are provided diagonally through the ridges Illa of spline section is to termination in nozzle openings in those lateral walls of ridges I 8a against which splines Ila normally rest.

Oil flow under pressure through the various oilfiow passages of the special conduit system 33, to alter the axial position of shaft l6 relative to driven gear I4, is thus directly controlledby the position of the valveheads 40 of control valve 32.

A by-pass oil passage 45 extends from commu-- nication withv valve passage 42, at a location offset, from the communicating ports of both oil flow passage 33c and oil-flow passage 33d, to the exterior surface of valve body 35. A by-pass oil conduit 46 connects'with passage 45 and extends to a return sump 41, Fig, 6, from where, the oil is returned to the reservoir 48 of the lubricating system by means of a return pump 49, disposed in I Thus, when the inflow port of oil-flow passage 33d is covered by a valve head 40, precluding flow of oil to the adjustable shaft coupling l5, there is merely a continuous oil reservoir 48 to oil-return sump 41, and return.

An oil-drain pipe may extend from commuto tightly hold the valve body 35 in I structure of the nication with the closed end of valve passage 42' back-pressure against the splines or vanes Ila by oil-entrapment, drain passages 54, Figs. 3,4,and 5, are provided, emptying into the chamber which is closed by bolt head 20a, see Fig. 3.

,Oil seals 52 may be provided, as found'necessary or advantageous, to prevent seepage loss of oil from the closed circulating system.

The movement of valve stem 4| with its associated valve head '40 is controlled by various pressure difierentials effective on the Sylphon or bellows 55, Figs. 4 and 6. The bellows 55 are disposed in a substantially gas tight chamber defined by an auxiliary housing 51, and are arranged in axial alignment with the valve stem 4|. .A hollow extension 4 I a of valve stem 4| passes hrough the chamber, and axially through bellows 55, into sliding engagement with a relatively short sleeve 58, fixed centrally of a circular end plate 55a of the bellows 55. An opposite circular end plate 55b of the bellows 55 is tightly secured intermediate the valvestem extension 4la. Accordingly, the end 55b of the bellows 55 is free to move the valve stem 4| back and forth relative to the fixedend 55a during expansion and contraction of the bellows.

The end plate 55a is inset into the tubular wall bellows 55 to form an externally cupped end extension 550; and a circumferential gasket 59, partially set in an internal circumferential groove 51a of the bellows housing 51, provides a pressure-tight seal between the outer pe riphery of such cupped end expansion 55c and the housing 51. Apertures 60 formed through bellows end plate 55a provide pressure communication between the thus sealed-oif terminal end portion of housing 51 and the interior of the belows.

In the above manner, the chamber formed by the housing 51 is divided into two portions GI and 52 by means-of the expansible and contractable bellows 55, and the valve 32 is operated in accordance with any expansion or contraction of the bellows.

Pursuant, to the invention, it is desired that the spark timing of the magneto ll relative 'to the engine Ill be varied in accordance with engine performance, and that the control be accomplished automatically by reason of varying differentials between pressures at two or more locations in the intake system of the engine.

In Fig. 6, where the various devices concerned in the specifically disclosed control system of the invention, as well as various conventional devices associated with the aircraft engine III, are illustrated schematically, the air scoop is designated 65, the-carburetor 66, the induction passage 51, the supercharger 58, and the intake manifold 69. The intake of air and gas is regulated manually by the pilot of the aircraft by means of a throttle control 10.

The differential pressures in this intake sysstem of the engine tion with the portion 52 or the pressure chainpassage by means of a pipe line 12, ex-.

valve stem extension a, for stabilizing the op-- eration of the bellows 55. g The placement of bellows 55 within the pressure chamber of housing 51 may be adiusted by removing or adding one or more shims Ii between the end plate 55a ofthe bellows and the tubular spacing post 15. Ports I6 are provided about the rim of the cupshaped extension 55c of the bellows to insure adequate entry of fluid from pressure pipe line 12 should adjustment of the position Of the bellows 55 within the pressure chamber bring the .extension 550 against the end wall 51b of auxiliary housing 51.

A cap screw and washer assembly, indicated generally 11, may be provided centrally of the end wall 51b of auxiliary housing '51 to provide entry of a suitable calibrating instrument during the testing of the device.

Operation Of'the spark timing control, just described structurally, is well set forth in the graph of Fig. 10, where, for a specific instance, the varying pressure differentials or metering forces, in terms of inches of mercury, are plotted against horsepower on propeller load. As indicated, when the metering force is between zero and approximately 5 inches of mercury, and the engine is exerting between and approximately 350' horsepower while idling, the spark is retarded; that is, the valve 32 is in the condition shown in Fig- 7, and the spline coupling I is in the relative position illustrated in Figs. 3, 4, and 5.

When the metering force is between approximately 5 :and approximately inches, and the engine is exerting between approximately 350 and approximately 1300 horsepower while running at cruising speed. the spark is advanced; that is, the valve 32 is in the condition shown in Fig. 8, and the spline coupling I5 is in theprelative position shown in Fig. 6, oil from conduit 33c being allowed to flow under pressure through conduits 33d and 33s and through jet conduits 331 against the splines Ila. When the metering forceis above approximately 15 inches, and the engine is exerting greater than approximately 1300 horsepower while running at high speed, the spark is retarded; that is, the valve 32 is in the position shown in Fig. 9, and the spline coupling 15 is back in the position shown in Figs. 3, 4, and 5, since there is no longer oil pressure operative to hold the spline section II in the forward osition relative to spline sec- I tion I8.

It is obvious that control systems similar to the one above described my be adapted to other types of internal combustion engines,whet er those engines are of aircraft, automotive, stationv ary, or other type, or whether they'emp'loy a plurality instead of a single supercharger, or no supercharger, and, also, that the control systems may be so arranged as to either'advance or retardthe spark setting in any desired specific re- 7 lationship to engine performance.

In the embodiment of Fig. '11, adapted for su tomotive use where superchargers are not ordi- 80 ployed for other important purposes.

aso eio narily employed,two throttles 80 and 9! are placed at spaced locations in the intake manifold 82 0f the engine at opposite sides of the carburetor 83. The two throttles are mechanically 5 linked together by a delay-action yoke 84 of conventional construction, and are operated in commen, as by the conventional accelerator device 95, the second throttle 8| being slightly delayed in its actuation, relative to the actuation of the i0 first throttle 90, by reason of the delay-action yoke.

intake manifold 82, at opposite sides of the second throttle 9|, by reason of the relationship 15 'between the two throttles, and fluid-pressure pipe lines BB-and 81, which correspond, respectively, to the fluid-pressure-pipe lines H and 12 of the prior embodiment, serve to tap these differential pressures and make them efiective on a Sylphon or bellows in exactly the same manner as aforedescribed with respect to the prior embodiment.

The advantageous pressure-sensitive diaphragm and thereby actuated valve arrangement afforded by the present invention for controlling accessory devices by reason of varying pressure differentials existing from time to time within the intake systems of internal combustion engines is not limitedin its use to automatically setting the spark timing of the engine, but may be em- In Figs. 12 and 13 is illustrated apparatus for opening and closing the adjustable cowling of an aircraft engine in accordance with engine performance from time to time.

The cowling 90 of the engine 9| has an adjustable rear flap 90a hinged to open and close with respect to a stationary wall portion 92, and pro-' viding, when open, an air flow channel 93, all as is conventional in present day aircraft. An arm 40 94, depending from the underside of cowling flap 90a, provides a connection for the intermediately jointedpush-pull adjusting rod 95.

The free end of rod 95 has a piston disk 99 fitted thereon, which is received within a pressure cylinder 91 for back and forth reciprocatory motionialong its length. A fluid-flow pipe line at communicates with the cylinder 91 adjacent the classed end thereof, and supplies pressure fluid, su as oil under pressure'from the lubricating system of the engine, as fully set forth in connection with the embodiment of Figs. 1 through .10,

to the cylinder in accordance with variations in engine performance from time to' time during operation of the aircraft.

Thatend of the cylinder '91 through which the rod 95 extends is closed by a circular plate 99, into and through a central aperture of which is threaded-a plug I00, provided with a central longitudinal bore through which the rod 9! slides.

A coil spring III of suitable resiliency is interposed'between the plug I00 and the piston disk 96 for normally maintaining the piston disk in operative position within its cylinder and the cowl flap 90a in open position. It, is only when there is fluid pressure in the pipe line 90 that the piston and connecting rod assembly holds the vcowl flap in closed position.

Provision is made for the pilot to manually adjust the degree of opening ofcowl flaps 90a.

A sprocket wheel I02 is mounted for free rotation on the rod 9!, being'held in place by a bracket piece I03. Pins I04 are anchored in the sprocket .wheel I02 and extend into corresponding receiving recesses I05 provided in the plug I00. the receases I" being sumcientiy long to allow 1 l.

Difierential pressures are provided within the a drive sprocket wheel I08 by a chain drive I01.

The drive sprocket wheel I08 is fixed on a shaft I which projects through the instrument panel llll. A knurled hand-wheel H is fixed on the projecting end of shaft I08, and affords means whereby the pilot of the aircraft may manually adjust the position of hinged flap 90a, and the size of the air flow opening 93, when desired. Because of the sprocket drive arrangement and of the pins I extending into receiving slots [05, the plug I" is screwed either backwardly or-forwardly relative to end plate 99 when the handwheel I I0 is rotated, thus moving the piston head 98 and its rod by reason of coil spring lfll.

In each of the above described specific embodiments of the invention, the fluid pressure employed to accomplish the actual adjustment and setting of devices accessory to the engine may be furnished by means other than the pressure oil system used for lubricating the engine. An auxiliary reservoir of any suitable fluid, as for instance of compressed air, may be provided to supply the desired fluid pressure.

If found suitable in particular instances, more than one pressure-responsive device, such as the bellows and pressure chamber here illustrated, may be employed to actuate the valve stem of the control valve 32, or the proper element of some other adjustment-control device. In such instances, the pressure-responsive devices may be arranged in tandemso their respective resultant responses may be collectively impressed upon such valve stem or other proper element. In this manner, several differential pressures existing within the intake system of an internal combustion en:

gine may be utilized to control the adjustment of a device or devices accessory to the engine.

Whereas this invention is here described with respect to preferred specific forms thereof, it should be understood that many changes may be made in such specific forms and that many other specific forms may be developed by those skilled in the art without departing from the spirit and generic purview of the invention as set forth herein and in the claims which here follow.

I claim:

neto sh'aft portion relative to and independent of said engine shaft portion, as well as maintenance of the new position of said magneto shaft portion so long as the said fluid under pressure is maintained in said conduit; means for supplying said conduit with fluid under pressure; valve means associated with said conduit means for controlling fluid flow from said fluid-pressure supplying means to said vane means; pressure-responsive means; means for impressing difierential'pressures, existing within the intake system of the said engine, upon said pressure-responsive means so as to effect response thereof in accordance with the resultant pressure differentials; and means for controlling said valve means in accordance with the varying responses of said pressure-responsive means occurring; from time to time during operation of said engine.

2. A system as recited in claim 1, wherein the means for supplying the fluid-pressure conduit with fluid under pressure constitutes the pressure oil system for lubricating the engine.

3. A system as recited in claim 1, wherein the shaft coupling is in the form of a loose spline connection, the magneto shaft portion having a male spline formation fitted into a, receiving socket formation of me engine shaft portion, and wherein the splines of the said male spline iormation provide the vane means against which fluid under pressure is projected by the fluid-pressure conduit means.

4. In ignition timing apparatus for an engine I having an induction system, an impellerior said induction system, first and second shafts drivabiy connected to the engine and timing apparatus respectively, coupling means between said shafts comprising a loosely interiltted axial spline connection permitting limited rotative movement between said shafts, and means operative to roo 'tatively advance said second shaft relative to said 1. A system for automatically changing the spark timing of an aircraft magnetorelative to an aircraft e ine in accordance with variations in engine performance from time to time, the magneto having driven means controlling the spark and spark timing relative to the engine, and the engine having drive means adapted to drive the said driven means of the magneto, said system comprising a variable shaft coupling connecting said engine drive means with said magneto driven means, said shaft coupling including a shaft portion fixed to said engine drive means and a separate shaft portion fixed to said magneto driven means, said shaft portions being so interengaged as to normally cause said magneto to be driven at one spark timing, but as to afford leeway for limited rotation of said magneto shaft portion,

relative to and independent of said engine shaft portion, to a position for causing said magneto to be driven at a different spark timing; vane means rigidly connected'with said magneto shaft portion; fluid-pressure conduit means terminating at said vane means and adapted to project fiuld under pressure against said vane means and to thus cause the said limited rotation of said magfirst shaft in response to the differential pressure across said impeller.

5. In ignition timing apparatus for an engine, a first shatt drivabiy connected to said engine, a second shaft connected to said timing apparatus, coupling drive means between said shafts comprising a loosely interfitted axial spline connection permitting limited rotative movement between said shafts, and means operative in response to a condition of said engine to rotatively advance said driven shaft relative to said driving shaft.

6. In ignition timing apparatus for an engine,

a first shaft drivably connected to said engine, a second shaft concentric with said first shaft and drivabiy connected to the timing apparatus, coupling means between said shafts comprising loosely interfitted axial driving abutments permitting limited rotative movement between said members, a source of fluid pressure, and means operative to apply said fluid pressure to said coupling to rotatively advance said second shaft relative to the first shaft.

7. In ignition timing apparatus for an engine. I

EARLQSETI'ERBLADE 

